CN111511641A

CN111511641A - Fiber sheet stacked rotor design

Info

Publication number: CN111511641A
Application number: CN201880082356.0A
Authority: CN
Inventors: S.泽韦克
Original assignee: Wing Aviation LLC
Current assignee: Wing Aviation LLC
Priority date: 2017-12-19
Filing date: 2018-12-06
Publication date: 2020-08-07
Anticipated expiration: 2038-12-06
Also published as: SG11202005579WA; FI3728025T3; EP3728025A4; EP3728025B1; US20190185143A1; WO2019125778A1; AU2018390426A1; EP4253038A3; EP3728025A1; CN111511641B; US11214356B2; US10689095B2; US20210039769A1; EP4253038A2; AU2022202951A1; AU2018390426B2

Abstract

A rotor unit is disclosed. The rotor unit includes a hub and stacked rotor blades. The hub is configured to rotate about an axis in a first rotational direction. The stacked rotor blade is rotatable about an axis and further includes a first blade element and a second blade element. The first blade element has a first leading edge and the second blade element has a second leading edge. The blade elements are arranged in a stacked configuration. The leading edge of the stacked rotor blade is formed from at least a portion of the first leading edge of the first blade element and at least a portion of the second leading edge of the second blade element. In some embodiments, the rotor unit is coupled to an unmanned aerial vehicle.

Description

Fiber sheet stacked rotor design

Cross Reference to Related Applications

This application claims priority to U.S. patent application No. 15/847,515 filed 2017, 12, 19, which is incorporated herein by reference in its entirety.

Technical Field

Background

Unless otherwise indicated herein, material described in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.

Unmanned vehicles, which may also be referred to as autonomous vehicles, are vehicles that are capable of traveling without the actual presence of human operators. The unmanned vehicle may operate in a remote control mode, in an autonomous mode, or in a partially autonomous mode.

When the unmanned vehicle is operating in a remote mode, a pilot or driver at a remote location may control the unmanned vehicle by commands sent to the unmanned vehicle via a wireless link. When unmanned vehicles operate in an autonomous mode, unmanned vehicles typically move based on preprogrammed navigation waypoints, dynamic automation systems, or a combination of these. Further, some unmanned vehicles may operate in both a remote control mode and an autonomous mode, and in some cases may do so simultaneously. For example, a remote pilot or driver may wish to delegate navigation to an autonomous system when manually performing another task (such as operating a mechanical system for picking up objects), as an example.

Various types of unmanned vehicles exist for a variety of different environments. For example, unmanned vehicles exist for operation in the air, on the ground, underwater, or in space. Examples include a quad-loader (quad-loader), a tailstock-type UAV, and the like. Unmanned vehicles also exist for hybrid operations in which multi-environment operations may be conducted. Examples of hybrid unmanned vehicles include amphibious airships capable of operating on land and on water, or seaplanes capable of landing on water and on land. Other examples are also possible.

Disclosure of Invention

Embodiments described herein relate to Unmanned Aerial Vehicle (UAV) rotor units having stacked rotor blades. Stacked rotor blades are formed from blade elements arranged in a stacked configuration. The blade element can be easily manufactured by a simple machining process, such as laser cutting the blade element from a fibre sheet. Furthermore, arranging the blade elements in a stacked configuration allows a high degree of control over the overall design and function of the assembled stacked rotor blade. Furthermore, the stacked rotor blades disclosed herein may also reduce the noise of UAV rotors during flight while maintaining or potentially improving efficiency as compared to existing rotor blade designs.

In a first aspect, a rotor unit is provided. The rotor unit includes a hub and stacked rotor blades. The hub is configured to rotate about an axis in a first rotational direction. The stacked rotor blade is rotatable about an axis and further includes a first blade element and a second blade element. The first blade element has a first leading edge and the second blade element has a second leading edge. Further, the first and second blade elements are arranged in a stacked configuration. In an example, the stacked configuration may result in the first and second blade elements being secured to one another in a particular alignment. In addition, the leading edge of the stacked rotor blade is formed from at least a portion of the first leading edge and at least a portion of the second leading edge. In some embodiments, the rotor unit is coupled to the UAV.

In a second aspect, a stacked rotor blade is provided. The stacked rotor blade includes a first planar blade element and a second planar blade element. The first blade element includes a first leading edge and a bottom planar surface, and the second blade element includes a second leading edge and a top planar surface. The bottom planar surface of the first blade element is secured to the top planar surface of the second blade element in a stacked configuration. The stacked rotor blades are configured to rotate in a first rotational direction. Further, at least a portion of the first leading edge of the first blade element leads at least a portion of the second leading edge of the second blade element in the first rotational direction. Additionally, at least a portion of the first leading edge and at least a portion of the second leading edge form a leading edge of the stacked rotor blade.

In yet another aspect, a method of manufacturing a stacked-blade rotor unit is provided. The method includes cutting a plurality of blade elements. The blade elements may be laser cut from a sheet of fibers or the like. At least one dimension of each vane element is different from a corresponding dimension in each of the other vane elements. Further, the leading edge of the stacked blade includes at least a portion of the leading edge from each cut blade element. The method also includes coupling the blade element to the hub.

In yet another aspect, any type of device or system may be used as or configured to perform the functions of any of the methods described herein (or any portion of the methods described herein). For example, a system for manufacturing stacked rotor blade units includes a device for cutting a plurality of blade elements. The system further comprises means for aligning the blade elements and means for coupling the blade elements to a hub of the rotor unit.

These and other aspects, advantages, and alternatives will become apparent to one of ordinary skill in the art by reading the following detailed description, where appropriate, with reference to the accompanying drawings. Furthermore, it is to be understood that the description provided elsewhere in this summary and this document is intended to be illustrative, and not restrictive, of the claimed subject matter.

Drawings

FIG. 1A is a simplified illustration of an Unmanned Aerial Vehicle (UAV) according to an example embodiment.

Fig. 1B is a simplified illustration of a UAV according to an example embodiment.

Fig. 1C is a simplified illustration of a UAV according to an example embodiment.

Fig. 1D is a simplified illustration of a UAV according to an example embodiment.

Fig. 1E is a simplified illustration of a UAV, according to an example embodiment.

FIG. 2 is a simplified block diagram illustrating components of an unmanned aerial vehicle according to an example embodiment.

Fig. 3 is a simplified block diagram illustrating a UAV system in accordance with an example embodiment.

FIG. 4 depicts a cross-section of a stacked rotor blade according to an example embodiment.

Figure 5 depicts a cross-section of a stacked rotor blade according to an example embodiment.

Figure 6A depicts a top view of a stacked-blade rotor unit according to an example embodiment.

Figure 6B depicts an elevational view of a stacked-blade rotor unit according to an example embodiment.

Figure 7 depicts stacked blade rotor units according to an example embodiment.

Figure 8 depicts a cross-section of a stacked-blade rotor unit according to an example embodiment.

Figure 9 depicts a cross-section of a stacked-blade rotor unit according to an example embodiment.

Figure 10 depicts a cross-section of a stacked-blade rotor unit according to an example embodiment.

Figure 11 depicts a top view of a stacked-blade rotor unit according to an example embodiment.

Figure 12 depicts a partial top view of a stacked-blade rotor unit according to an example embodiment.

FIG. 13 is a block diagram of an example method in accordance with an example embodiment.

Detailed Description

Example methods, systems, and apparatus are described herein. Any example embodiment or feature described herein is not necessarily to be construed as preferred or advantageous over other embodiments or features. The example embodiments described herein are not meant to be limiting. It will be readily understood that certain aspects of the disclosed systems and methods may be arranged and combined in a wide variety of different configurations, all of which are contemplated herein.

Furthermore, the particular arrangement shown in the drawings should not be considered limiting. It should be understood that other embodiments may include more or less of each element shown in a given figure. In addition, some of the illustrated elements may be combined or omitted. Furthermore, example embodiments may include elements not shown in the figures.

I. Overview

The exemplary embodiments may be implemented or employed in the form of an aircraft; such as an Unmanned Aerial Vehicle (UAV). In an example embodiment, the UAV may include a "propulsion unit" or "rotor unit" operable to provide thrust or lift to the UAV for transport and delivery of cargo.

Low reynolds number hydrodynamic conditions for the bladeletts, such as those used in UAV flight as described herein, do not penalize a small step or matte rotor blade design. Accordingly, creating multiple blade elements from a sheet of fiber or other similar material, and then stacking the blade elements in a stacked configuration to form a stacked rotor blade, allows for a variety of rotor blade designs at lower manufacturing costs. Such a design reduces the need for expensive tooling arrangements that result in expensive scaling operations. Instead, stacked fiber-sheet rotor blades allow each blade element to be shaped to produce the flight equivalent of a monolithic propeller profile. In some examples, the effective profile of the cross-section of the stacked rotor blades may be the same as or similar to the profile of a conventional airfoil. However, it is easier and simpler to mass produce individual blade elements with existing manufacturing equipment, which can then be combined to produce the necessary rotor design. Furthermore, the stacked rotor blades allow for easy custom design to produce rotors for specific tasks, and allow for various designs to be tailored with stacked rotor blade designs to reduce or minimize noise from the UAV. Additionally, some example stacked rotor blade designs disclosed herein may reduce the amount of noise generated by UAV rotors in flight. For example, the blade elements may comprise piezoelectric patches, which may allow further acoustic control, such as increased rotor harmonic control.

The drawings described in detail below are for illustration purposes only and may not reflect all of the components or connections. Further, as an illustration, the figures may not reflect actual operating conditions, but are merely intended to illustrate the described embodiments. Furthermore, the relative dimensions and angles in the drawings may not be to scale, but are merely intended to illustrate the described embodiments.

Schematic unmanned vehicle

Here, the terms "unmanned aerial vehicle" and "UAV" refer to any autonomous or semi-autonomous vehicle capable of performing some function without an actual human pilot.

UAVs may take various forms. For example, UAVs may take the form of fixed wing aircraft, gliders, tail-stock aircraft, jet aircraft, ducted fan aircraft, lighter-than-air airships (such as blimps or steerable balloons), rotorcraft (such as helicopters or multi-axis aircraft), and/or ornithopters, among others. Furthermore, the terms "drone," "unmanned aerial vehicle system" (UAVS), or "unmanned aerial system" (UAS) may also be used to refer to a UAV.

Fig. 1A is an isometric view of an example UAV 100. UAV100 includes wings 102, a boom 104, and a fuselage 106. The wings 102 may be fixed and may generate lift based on the wing shape and the forward airspeed of the UAV. For example, both wings 102 may have an airfoil shaped cross section to generate aerodynamic forces on UAV 100. In some embodiments, the wing 102 may carry a horizontal propulsion unit 108 and the boom 104 may carry a vertical propulsion unit 110. In operation, power for the propulsion unit may be provided from the battery compartment 112 of the fuselage 106. In some embodiments, fuselage 106 also includes avionics bay 114, an additional battery bay (not shown), and/or a delivery unit (not shown, e.g., a winch system) for handling cargo. In some embodiments, fuselage 106 is modular, and two or more compartments (e.g., battery compartment 112, avionics compartment 114, other cargo and delivery compartments) are detachable from one another (e.g., mechanically, magnetically, or otherwise) and securable to one another to continuously form at least a portion of fuselage 106.

In some embodiments, boom 104 terminates in rudder 116 to improve yaw control of UAV 100. Further, the wings 102 may terminate in wing tips 117 to improve lift control for the UAV.

In the configuration shown, UAV100 includes a structural frame. This structural frame may be referred to as the "structural H-frame" or "H-frame" (not shown) of the UAV. The H-frame may include wing spars (not shown) within the wing 102 and boom supports (not shown) within the boom 104. In some embodiments, the wing spars and boom brackets may be made of carbon fiber, hard plastic, aluminum, light metal alloys, or other materials. The wing spar and the boom support may be connected with a clamp. The wing spars may include pre-drilled holes for the horizontal propulsion units 108 and the boom supports may include pre-drilled holes for the vertical propulsion units 110.

In some embodiments, the fuselage 106 may be removably attached to the H-frame (e.g., to a wing spar via a clip or the like configured with grooves, protrusions, or other features to mate with corresponding H-frame features). In other embodiments, similarly, the fuselage 106 may be removably attached to the wing 102. The removable attachment of fuselage 106 may improve the mass and/or modularity of UAV 100. For example, electrical/mechanical components and/or subsystems of airframe 106 may be tested separately from the H-frame prior to attachment to the H-frame. Similarly, the Printed Circuit Board (PCB)118 may be tested separately from the boom support prior to attachment to the boom support, thus eliminating defective parts/subassemblies prior to completion of the UAV. For example, electrical testing may be performed on components of the airframe 106 (e.g., avionics, battery units, delivery units, additional battery bays, etc.) prior to mounting the airframe 106 to the H-frame. In addition, the motors and electronics of the PCB 118 may also be electrically tested prior to final assembly. Generally, identifying defective parts and sub-assemblies early in the assembly process reduces the overall cost and delivery time of the UAV. Further, different types/models of airframe 106 may be attached to the H-frame, thus improving the modularity of the design. Such modularity allows these various parts of UAV100 to be upgraded without substantial major repairs to the manufacturing process.

In some embodiments, the wing and boom shells may be attached to the H-frame by adhesive elements (e.g., tape, double-sided tape, glue, etc.). Thus, multiple shells may be attached to the H-frame, rather than spraying a unitary body onto the H-frame. In some embodiments, the presence of the plurality of shells reduces stresses caused by the coefficient of thermal expansion of the structural frame of the UAV. As a result, the UAV may have better dimensional accuracy and/or improved reliability.

Furthermore, in at least some embodiments, the same H-frame may be used with wing shells and/or boom shells having different sizes and/or designs, thus increasing the modularity and versatility of the UAV design. The wing and/or boom shells may be made of a relatively light polymer (e.g. closed cell foam) covered by a relatively stiff but relatively thin plastics skin.

Power and/or control signals from the fuselage 106 may be routed to the PCB 118 through cables that pass through the fuselage 106, the wing 102, and the boom 104. In the illustrated embodiment, UAV100 has four PCBs, but other numbers of PCBs are possible. For example, UAV100 may include two PCBs, one for each boom. The PCB carries electronic components 119, the electronic components 119 including for example power converters, controllers, memories, passive components etc. In operation,

propulsion units

108 and 110 of UAV100 are electrically connected to the PCB.

Many variations of the UAV shown are possible. For example, a fixed-wing UAV may include more or fewer rotor units (vertical or horizontal), and/or may utilize a ducted fan or fans for propulsion. Further, UAVs with more wings (e.g., an "x-wing" configuration with four wings) are also possible. Although fig. 1 shows two wings 102, two booms 104, two horizontal propulsion units 108, and six vertical propulsion units 110 per boom 104, it should be understood that other variations of UAV100 may be implemented with more or fewer of these components. For example, UAV100 may include four wings 102, four booms 104, and more or fewer propulsion units (horizontal or vertical).

Similarly, fig. 1B shows another example of a fixed-wing UAV 120. The fixed wing UAV 120 includes a fuselage 122, two wings 124 having an airfoil shaped cross-section to provide lift to the UAV 120, a vertical stabilizer 126 (or ventral fin) to stabilize the yaw (left or right turns) of the aircraft, a horizontal stabilizer 128 (also known as a lift or tail) to stabilize the pitch (up or down tilt), landing gear 130, and a propulsion unit 132, which propulsion unit 132 may include a motor, shaft, and propeller.

Fig. 1C shows an example of a UAV 140 having a propeller in a propulsive configuration. The term "propelled" refers to the fact that the propulsion unit 142 is mounted at the rear of the UAV and "propels" the vehicle forward, as compared to mounting the propulsion unit at the front of the UAV. Similar to the description provided for fig. 1A and 1B, fig. 1C depicts a conventional structure used in a propelled aircraft, including a fuselage 144, two wings 146, vertical stabilizers 148, and a propulsion unit 142, which propulsion unit 142 may include a motor, a shaft, and a propeller.

Fig. 1D shows an example of a tailstock-type UAV 160. In the example shown, the tailstock-style UAV160 has fixed wings 162 to provide lift and allow the UAV160 to glide horizontally (e.g., along the x-axis, at a position approximately perpendicular to the position shown in fig. 1D). However, the fixed wings 162 also allow the aft UAV160 to take-off and land vertically on its own.

For example, at the launch point, the tailstock-style UAV160 may be placed vertically (as shown), with its ventral wings 164 and/or wings 162 resting on the ground and stabilizing the UAV160 in a vertical position. The aft-seated UAV160 may then take off by operating its propeller 166 to generate upward thrust (e.g., thrust generally along the y-axis). Once at the proper altitude, the tailstock-style UAV160 may reorient itself in a horizontal position using its flaps 168 so that its fuselage 170 is aligned closer to the x-axis than to the y-axis. The horizontally disposed propellers 166 may provide forward thrust so that the aft-seated UAV160 can fly in a similar manner as a typical airplane.

Many variations on the illustrated fixed-wing UAV are possible. For example, the fixed-wing UAV may include more or fewer propellers and/or may utilize a ducted fan or fans for propulsion. Further, UAVs with more wings (e.g., "x-wing" configuration with four wings), with fewer wings, or even without wings are also possible.

As noted above, some embodiments may involve other types of UAVs in addition to or in lieu of fixed wing UAVs. For example, fig. 1E shows an example of a rotary wing vehicle commonly referred to as a multi-axis vehicle 180. The multi-axis vehicle 180 may also be referred to as a quad-rotor vehicle because it includes four rotors 182. It should be appreciated that example embodiments may relate to rotorcraft having more or fewer rotors than multi-axis aircraft 180. For example, helicopters typically have two rotors. Other examples with three or more rotors are also possible. Here, the term "multi-axis aircraft" refers to any rotorcraft having more than two rotors, and the term "helicopter" refers to a rotorcraft having two rotors.

Referring in more detail to multi-axis vehicle 180, four rotors 182 provide thrust and maneuverability for multi-axis vehicle 180. More specifically, each rotor 182 includes a blade attached to an electric motor 184. So configured, the rotor 182 may allow the multi-axis aircraft 180 to take off and land vertically, maneuver in any direction, and/or hover. Further, the pitch of the blades may be adjusted in groups and/or differently, and may allow multi-axis vehicle 180 to control its pitch, roll, yaw, and/or altitude.

It should be understood that references herein to "unmanned" aircraft or UAV may apply equally to autonomous and semi-autonomous aircraft. In an autonomous embodiment, all functions of the aircraft are automated; for example, pre-programmed or controlled by real-time computer functions in response to inputs from various sensors and/or predetermined information. In a semi-autonomous embodiment, some functions of the aircraft may be controlled by a human operator, while other functions are performed autonomously. Further, in some embodiments, the UAV may be configured to allow a remote operator to take over functions that may otherwise be autonomously controlled by the UAV. Still further, functions of a given type may be remotely controlled at one level of abstraction and autonomously performed at another level of abstraction. For example, the remote operator may control advanced navigation decisions of the UAV, such as by specifying that the UAV should travel from one location to another (e.g., from a warehouse in a suburban area to a delivery address in a nearby city), while the UAV's navigation system autonomously controls finer-grained navigation decisions, such as a particular route taken between two locations, particular flight controls to implement the route and avoid obstacles while navigating the route, and so forth.

More generally, it should be understood that the example UAVs described herein are not intended to be limiting. Example embodiments may relate to, be implemented in, or take the form of any type of unmanned aerial vehicle.

Exemplary UAV Components

Fig. 2 is a simplified block diagram illustrating components of a UAV200 according to an example embodiment. The UAV200 may take the form of, or be similar in form to, one of the

UAVs

1100a, 120, 140, 160, and 180 described with reference to fig. 1A-1E. However, the UAV200 may take other forms as well.

UAV200 may include various types of sensors and may include a computing system configured to provide the functionality described herein. In the illustrated embodiment, the sensors of the UAV200 include an Inertial Measurement Unit (IMU)202, ultrasonic sensor(s) 204, and a GPS 206, among other possible sensors and sensing systems.

In the illustrated embodiment, the UAV200 also includes one or more processors 208. The processor 208 may be a general-purpose processor or a special-purpose processor (e.g., a digital signal processor, an application specific integrated circuit, etc.). The one or more processors 208 may be configured to execute computer-readable program instructions 212, the computer-readable program instructions 212 being stored in the data store 210 and operable to provide the functionality of the UAV described herein.

The data store 210 can include, or take the form of, one or more computer-readable storage media readable or accessible by the at least one processor 208. The one or more computer-readable storage media may include volatile and/or nonvolatile storage components, such as optical, magnetic, organic, or other memory or disk storage, which may be integrated in whole or in part with at least one of the one or more processors 208. In some embodiments, the data store 210 may be implemented using a single physical device (e.g., one optical, magnetic, organic, or other memory or disk storage unit), while in other embodiments, the data store 210 may be implemented using two or more physical devices.

As noted, the data store 210 may include computer-readable program instructions 212 and possibly additional data, such as diagnostic data for the UAV 200. As such, the data store 210 may include program instructions 212 to perform or facilitate some or all of the UAV functions described herein. For example, in the illustrated embodiment, the program instructions 212 include a navigation module 214 and a tether control module 216.

In some embodiments, the control system 1120 may take the form of the program instructions 212 and one or more processors 208.

A. Sensor with a sensor element

In an exemplary embodiment, the IMU 202 may include both an accelerometer and a gyroscope, which may be used together to determine the orientation of the UAV 200. In particular, an accelerometer may measure the orientation of the vehicle relative to the earth, while a gyroscope measures the rate of rotation about an axis. The IMU is a commercially available low cost, low power consumption package (package). For example, the IMU 202 may take the form of or include a miniaturized microelectromechanical system (MEMS) or nanoelectromechanical system (NEMS). Other types of IMUs may also be utilized.

In addition to accelerometers and gyroscopes, the IMU 202 may include other sensors that may help to better determine location and/or help to increase autonomy of the UAV 200. Two examples of such sensors are magnetometers and pressure sensors. In some embodiments, the UAV may include a low-power digital 3-axis magnetometer that can be used to implement an orientation-independent electronic compass to obtain accurate heading information. However, other types of magnetometers may also be utilized. Other examples are also possible. Further, note that the UAV may include some or all of the inertial sensors described above as a separate component from the IMU.

UAV200 may also include a pressure sensor or barometer that may be used to determine the altitude of UAV 200. Alternatively, other sensors (such as sonic altimeters or radar altimeters) may be used to provide an altitude indication, which may help to improve the accuracy of the IMU and/or prevent drift of the IMU.

In another aspect, the UAV200 may include one or more sensors that allow the UAV to sense objects in the environment. for example, in the illustrated embodiment, the UAV200 includes ultrasonic sensor(s) 204. the ultrasonic sensor(s) 204 may determine distance to objects by generating sound waves, determining the time interval between the transmission of waves, and receiving corresponding echoes off of objects.

In some embodiments, UAV200 may also include one or more imaging systems. For example, UAV200 may utilize one or more still cameras and/or video cameras to capture image data from the UAV's environment. As a specific example, a Charge Coupled Device (CCD) camera or a Complementary Metal Oxide Semiconductor (CMOS) camera may be used with the unmanned vehicle. Such imaging sensor(s) have many possible applications, such as obstacle avoidance, positioning techniques, ground tracking for more accurate navigation (e.g., by applying optical flow techniques to the images), video feedback, and/or image recognition and processing, among others.

The UAV200 may also include a GPS receiver 206. The GPS receiver 206 may be configured to provide data typical of well-known GPS systems, such as GPS coordinates of the UAV 200. UAV200 may utilize such GPS data for various functions. As such, the UAV may use its GPS receiver 206 to assist in navigating to the location of the caller as indicated by the GPS coordinates provided at least in part by its mobile device. Other examples are also possible.

B. Navigation and location determination

The navigation module 214 may provide functionality that allows the UAV200 to move, for example, within its environment and reach a desired location. To this end, the navigation module 214 may control the altitude and/or direction of flight by controlling mechanical features of the UAV that affect flight, such as its rudder(s), elevator(s), aileron(s), and/or its propeller(s).

The UAV200 may be able to navigate in an unknown environment using positioning via position-based navigation.positioning-based navigation may involve the UAV200 building its own environment map and calculating its location within the map and/or the location of objects in the environment.

In some implementations, the navigation module 214 can navigate using waypoint-dependent techniques. In particular, a waypoint is a set of coordinates that identifies a point in physical space. For example, an air navigation waypoint may be defined by a latitude, a longitude, and an altitude. Thus, the navigation module 214 may move the UAV200 from one waypoint to another in order to finally travel to a final destination (e.g., a final waypoint in a series of waypoints).

In another aspect, the navigation module 214 and/or other components and systems of the UAV200 may be configured to "locate" to more accurately navigate to the scene of the target location. More specifically, in certain situations, it may be desirable for the UAV to be within a threshold distance of the target location at which the payload 228 is delivered by the UAV (e.g., within a few feet of the target destination). To this end, the UAV may use a dual approach in which it navigates to an approximate area associated with the target location using a general location determination technique, and then uses a more precise location determination technique to identify and/or navigate to the target location within the approximate area.

For example, the UAV200 may navigate to the approximate area of the target destination to which the payload 228 is being delivered using waypoint and/or map-based navigation. The UAV may then switch to a mode in which it utilizes positioning and proceeds to a more specific location positioning process. For example, if the UAV200 were to deliver a payload to the user's home, the UAV200 would need to be substantially close to the target location to avoid delivering the payload to an undesired area (e.g., on the roof, in a swimming pool, in a neighboring yard, etc.). However, the GPS signal may only enable the UAV200 to go there (e.g., within the user's residential area). More accurate location determination techniques can then be used to find a specific target location.

Once the UAV200 has navigated to the general area of the target delivery location, various types of location determination techniques may be used to complete the location of the target delivery location. For example, the UAV200 may be equipped with one or more sensor systems, such as, for example, ultrasonic sensors 204, infrared sensors (not shown), and/or other sensors, which may provide input that the navigation module 214 uses to autonomously or semi-autonomously navigate to a particular target location.

As another example, once UAV200 reaches the general area of a target delivery location (or a movable body such as a person or their mobile device), UAV200 may switch to a "fly-by-wire" mode in which it is controlled, at least in part, by a remote operator, who may navigate UAV200 to a particular target location. To do so, sensed data from the UAV200 may be sent to a remote operator to assist them in navigating the UAV200 to a particular location.

As yet another example, UAV200 may include a module capable of signaling passersby to assist in reaching a particular target delivery location; for example, the UAV200 may display a visual message requesting such assistance in a graphical display, play an audio message or tone through a speaker to indicate that such assistance is needed, and so forth. Such visual or audio messages may indicate that assistance is needed in delivering UAV200 to a particular person or location, and may provide information to assist passersby in delivering UAV200 to the person or location (e.g., a description or picture of the person or location, and/or a name of the person or location), and so forth. Such features may be useful in scenarios where the UAV cannot use sensory functions or other position determination techniques to reach a particular target location. However, such features are not limited to such scenarios.

In some implementations, once the UAV200 reaches the approximate area of the target delivery location, the UAV200 may locate the person using beacons from a remote device of the user (e.g., the user's mobile phone). Such beacons may take various forms. As an example, consider a scenario in which a remote device (such as a mobile phone of a person requesting UAV delivery) is able to issue a directional signal (e.g., via RF signals, light signals, and/or audio signals). In such a scenario, UAV200 may be configured to navigate through such directional signals as "back to the source" -in other words, by determining the location where the signal is strongest and navigating accordingly. As another example, the mobile device may transmit a frequency that is within or outside of human range, and the UAV200 may listen to the frequency and navigate accordingly. As a related example, if the UAV200 is listening to a spoken command, the UAV200 may utilize a protocol such as "I am here! "to trace the specific location of the person requesting delivery of the shipment.

In an alternative arrangement, the navigation module may be implemented at a remote computing device in wireless communication with the UAV 200. The remote computing device may receive data from UAV200 indicative of the operational state of UAV200, sensor data that allows the remote computing device to assess environmental conditions that UAV200 is experiencing and/or location information of UAV 200. With such information, the remote computing device may determine the altitude and/or directional adjustments that UAV200 should make, and/or may determine how UAV200 should adjust its mechanical characteristics (e.g., the speed of its rudder(s), elevator(s), aileron(s), and/or its propeller (s)) in order to effect such movement. The remote computing system may then communicate such adjustments to the UAV200 so that it may move in a determined manner.

C. Communication system

In another aspect, UAV200 includes one or more communication systems 218. communication systems 218 may include one or more wireless interfaces and/or one or more wired interfaces that allow UAV200 to communicate via one or more networks such wireless interfaces may provide for communication under one or more wireless communication protocols, such as Bluetooth, WiFi (e.g., IEEE 802.11 protocol), Long term evolution (L TE), WiMAX (e.g., IEEE 802.16 standard), radio-frequency ID (RFID) protocol, Near Field Communication (NFC), and/or other wireless communication protocols.

In some embodiments, UAV200 may include a communication system 218 that allows for both short-range and long-range communications. For example, the UAV200 may be configured for short-range communications using bluetooth and for long-range communications under CDMA protocols. In such embodiments, UAV200 may be configured to function as a "hot spot"; or in other words as a gateway or proxy between the remote support device and one or more data networks, such as a cellular network and/or the internet. So configured, the UAV200 may facilitate data communications that the remote support device would otherwise be unable to perform by itself.

For example, UAV200 may provide a WiFi connection with a remote device and act as a proxy or gateway to a cellular service provider's data network to which the UAV may connect under, for example, L TE or 3G protocols UAV200 may also act as a proxy or gateway to a high-altitude balloon network, satellite network, or a combination of these networks, etc., that the remote device may otherwise have no access to.

D. Electric power system

In another aspect, UAV200 may include electrical power system(s) 220. The power system 220 may include one or more batteries for providing power to the UAV 200. In one example, the one or more batteries may be rechargeable, each of which may be charged via a wired connection between the battery and a power source and/or via a wireless charging system (such as an inductive charging system that applies an external time-varying magnetic field to an internal battery).

E. Carrier delivery

The UAV200 may employ various systems and configurations for transporting and delivering the payload 228. In some embodiments, the payload 228 of a given UAV200 may include or take the form of "packages" designed to transport various cargo to a target delivery location. For example, the UAV200 may include a compartment in which an item or items may be transported. Such a package may be one or more food items, purchased merchandise, medical items, or any other object(s) having a size and weight suitable for transport by the UAV between two locations. In other embodiments, the payload 228 may simply be one or more items being delivered (e.g., without any packaging containing the items).

In some embodiments, the payload 228 may be attached to and substantially external to the UAV during some or all flights of the UAV. For example, the package may be tethered or otherwise releasably attached beneath the UAV during flight to the target location. In embodiments where the package carries cargo below the UAV, the package may include various features that protect its contents from the environment, reduce the lost motion drag on the system, and prevent the contents of the package from shifting during the UAV flight.

For example, when the payload 228 takes the form of a package for transporting items, the package may include an outer shell constructed of waterproof cardboard, plastic, or any other lightweight and waterproof material. Further, to reduce drag, the wrap may feature a smooth surface with a pointed front portion that reduces the cross-sectional area of the front portion. Furthermore, the sides of the package may taper from a wide bottom to a narrow top, which allows the package to act as a narrow tower (pylon) that reduces the interfering effects on the wing(s) of the UAV. This may keep some of the forward area and volume of the package away from the wing(s) of the UAV, preventing a package-induced reduction in lift on the wing(s). Further, in some embodiments, the outer shell of the package may be constructed from a single sheet of material in order to reduce air gaps or additional material, both of which may increase resistance to the system. Additionally or alternatively, the wrap may include a stabilizer to inhibit flutter of the wrap. This reduction in tremor may allow the package to have less rigid connection with the UAV, and may cause the contents of the package to less displace during flight.

To deliver the payload, the UAV may include a winch system 221 controlled by the tether control module 216 to lower the payload 228 to the ground while the UAV hovers above. As shown in fig. 2, the winch system 221 may include a tether 224, and the tether 224 may be coupled to a payload 228 via a payload coupling device 226. The tether 224 may be wound on a spool of a motor 222 coupled to the UAV. The motor 222 may take the form of a DC motor (e.g., a servo motor) that may be actively controlled by a speed controller. The tether control module 216 may control the speed controller to cause the motor 222 to rotate the spool to unwind or retract the tether 224 and lower or raise the payload coupling device 226. In practice, the speed controller may output a desired operating rate (e.g., a desired RPM) for the spool, which may correspond to the speed at which the tether 224 and payload 228 should be lowered toward the ground. The motor 222 can then rotate the spool so that it maintains the desired operating rate.

To control the motor 222 via the speed controller, the tether control module 216 may receive data from a speed sensor (e.g., an encoder) configured to convert the mechanical position to a representative analog or digital signal. In particular, the speed sensor may comprise a rotary encoder that may provide information about the rotational position (and/or rotational movement) of a shaft of the motor or a spool coupled to the motor, or the like. Further, the speed sensor may take the form of an absolute encoder and/or an incremental encoder, etc. Thus, in an example embodiment, when the motor 222 causes rotation of the spool, a rotary encoder may be used to measure the rotation. In doing so, the rotary encoder may be used to convert the rotational position to an analog or digital electronic signal used by the tether control module 216 to determine the amount of rotation of the spool from a fixed reference angle and/or to convert the rotational position to an analog or digital electronic signal representative of a new rotational position, among other options. Other examples are also possible.

Based on data from the speed sensor, the tether control module 216 may determine the rotational speed of the motor 222 and/or the spool and responsively control the motor 222 (e.g., by increasing or decreasing the current supplied to the motor 222) to match the rotational speed of the motor 222 to a desired speed. When adjusting the motor current, the magnitude of the current adjustment may be based on a Proportional Integral Derivative (PID) calculation using the determined and desired speed of the motor 222. For example, the magnitude of the current adjustment may be based on a current difference between the determined and desired speeds of the spools, a past difference (based on accumulated error over time), and a future difference (based on a current rate of change).

In some embodiments, the tether control module 216 may vary the rate at which the tether 224 and payload 228 are lowered to the ground. For example, the speed controller may vary the desired operating rate in accordance with a variable deployment rate profile (deployment-rate profile) and/or in response to other factors in order to vary the rate at which the payload 228 is lowered toward the ground. To this end, the tether control module 216 may adjust the amount of braking or friction applied to the tether 224. For example, to change the deployment rate of the tether, the UAV200 may include a friction pad that may apply a variable amount of pressure to the tether 224. As another example, the UAV200 may include an electric brake system that varies the rate at which the spool pays out the tether 224. Such a braking system may take the form of an electromechanical system in which the motor 222 operates to slow the reel-out of the tether 224. Further, the motor 222 may vary the amount by which it adjusts the speed (e.g., RPM) of the spool, and thus may vary the deployment rate of the tether 224. Other examples are also possible.

In some embodiments, the tether control module 216 may be configured to limit the motor current supplied to the motor 222 to a maximum value. With such a limit set on the motor current, there may be situations where the motor 222 is unable to operate at the desired operation specified by the speed controller. For example, as discussed in more detail below, there may be circumstances where the speed controller specifies a desired operating rate at which the motor 222 should retract the tether 224 toward the UAV200, but the motor current may be limited such that a sufficiently large downward force on the tether 224 will counteract the retraction force of the motor 222 and, instead, unwind the tether 224. As discussed further below, the limit on the motor current may be imposed and/or altered depending on the operating state of UAV 200.

In some embodiments, the tether control module 216 may be configured to determine the status of the tether 224 and/or the payload 228 based on the amount of current supplied to the motor 222. For example, if a downward force is applied to the tether 224 (e.g., if the payload 228 is attached to the tether 224, or if the tether 224 hooks over an object when retracted toward the UAV 200), the tether control module 216 may need to increase the motor current in order to match the determined rotational speed of the motor 222 and/or spool to the desired speed. Similarly, when downward force is removed from the tether 224 (e.g., after delivery of the payload 228 or removal of tether hooking), the tether control module 216 may need to reduce the motor current in order to match the determined rotational speed of the motor 222 and/or spool to the desired speed. As such, the tether control module 216 may determine whether the payload 228 is attached to the tether 224, whether a person or thing is pulling on the tether 224, and/or whether the payload coupling device 226 is abutting the UAV200 after retracting the tether 224 based on the current supplied to the motor 222. Other examples are also possible.

During delivery of the payload 228, the payload coupling apparatus 226 may be configured to secure the payload 228 while being lowered from the UAV by the tether 224, and may be further configured to release the payload 228 upon reaching the ground. The payload coupling apparatus 226 can then be retracted to the UAV by using the motor 222 to wind in the tether 224.

In some embodiments, once the payload 228 is lowered to the surface, it may be passively released. For example, the passive release mechanism may comprise one or more swing arms adapted to retract into and extend from the housing. The extended swing arms may form hooks on which the payload 228 may be attached. As the release mechanism and payload 228 are lowered to the ground via the tether, gravity and downward inertial forces on the release mechanism may disengage the payload 228 from the hook, which allows the release mechanism to be raised upward toward the UAV. The release mechanism may also include a spring mechanism that biases the swing arm to retract into the housing when there is no other external force on the swing arm. For example, the spring may apply a force to the swing arm that pushes or pulls the swing arm toward or toward the housing such that the swing arm retracts into the housing once the weight of the payload 228 no longer forces the swing arm to extend from the housing. Retracting the swing arms into the housing may reduce the likelihood of the release mechanism snagging on the payload 228 or other nearby objects when the release mechanism is raised toward the UAV after delivery of the payload 228.

Active payload release mechanisms are also possible. For example, a sensor such as an altimeter and/or accelerometer based on atmospheric pressure may help detect the position of the release mechanism (and the payload) relative to the ground. Data from the sensors may be transmitted back to the UAV and/or control system over a wireless link and used to help determine when the release mechanism reaches the ground (e.g., by detecting measurements with an accelerometer that characterizes ground impacts). In other examples, the UAV may determine that the payload has reached the ground based on a weight sensor detecting a threshold low downward force on a tether and/or based on a threshold low measurement of power drawn by a winch when the payload is lowered.

Other systems and techniques for delivering the payload are possible in addition to or in lieu of the tethered delivery system. For example, UAV200 may include an airbag descent system or a parachute descent system. Alternatively, UAV200 carrying a payload may simply land on the ground at the delivery location. Other examples are also possible.

Schematic UAV deployment system

UAV systems may be implemented to provide various UAV related services. In particular, UAVs may be provided at many different launch points that may communicate with regional control systems and/or central control systems. Such a distributed UAV system may allow UAVs to be deployed quickly to provide services across a large geographic area (e.g., much larger than the flight range of any single UAV). For example, UAVs capable of carrying cargo may be distributed at many launch points across a large geographic area (possibly even throughout the entire country, or even throughout the world) to provide on-demand transportation of various items to locations within the entire geographic area. Fig. 3 is a simplified block diagram illustrating a distributed UAV system 300 in accordance with an example embodiment.

In the exemplary UAV system 300, the access system 302 may allow for network interaction with the UAV304, control of the network of the UAV304, and/or utilize the network of the UAV 304. In some implementations, the access system 302 can be a computing system that allows for human-controlled dispatch of the UAV 304. As such, the control system may include or otherwise provide a user interface through which a user may access and/or control UAV 304.

In some implementations, the scheduling of the UAV304 may additionally or alternatively be achieved via one or more automated processes. For example, the access system 302 may schedule one of the UAVs 304 to transport a payload to a target location, and the UAV may navigate to the target location autonomously by utilizing various onboard sensors (such as a GPS receiver and/or other various navigation sensors).

Further, the access system 302 may provide for remote operation of the UAV. For example, the access system 302 may allow an operator to control the flight of a UAV via a user interface of the UAV. As a specific example, an operator may use access system 302 to dispatch UAV304 to a target location. UAV304 may then autonomously navigate to the approximate area of the target location. In this regard, an operator may use the access system 302 to control the UAV304 and navigate the UAV to a target location (e.g., to a particular person to whom the payload is being transported). Other examples of remote operation of UAVs are also possible.

In an exemplary embodiment, the UAV304 may take various forms. For example, each UAV304 may be a UAV such as shown in fig. 1A-1E. However, other types of UAVs may also be utilized by the UAV system 300 without departing from the scope of the present invention. In some embodiments, all UAVs 304 may have the same or similar configuration. However, in other embodiments, UAV304 may comprise many different types of UAVs. For example, UAV304 may include many types of UAVs, where each type of UAV is configured for a different type or types of payload delivery capabilities.

The UAV system 300 may also include a remote device 306 that may take various forms. In general, the remote device 306 may be any device through which a direct or indirect request to schedule a UAV may be issued. (Note that an indirect request may involve any communication that may be responded to by scheduling a UAV, such as requesting package delivery). In an example implementation, the remote device 306 may be a mobile phone, a tablet computer, a laptop computer, a personal computer, or any network connected computing device. Further, in some cases, remote device 306 may not be a computing device. As an example, a standard telephone that allows communication via Plain Old Telephone Service (POTS) may be used as the remote device 306. Other types of remote devices are also possible.

Further, remote device 306 may be configured to communicate with access system 302 via one or more types of communication network(s) 308. For example, the remote device 306 may communicate with the access system 302 (or a human operator of the access system 302) by communicating over a POTS network, a cellular network, and/or a data network such as the internet. Other types of networks may also be utilized.

In some implementations, the remote device 306 may be configured to allow a user to request delivery of one or more items to a desired location. For example, a user may request UVA delivery of a package to their home via their mobile phone, tablet, or laptop. As another example, a user may request a dynamic delivery to the location they were at the time of delivery. To provide such dynamic delivery, the UAV system 300 may receive location information (e.g., GPS coordinates, etc.) from the user's mobile phone or any other device on the user so that the UAV may navigate to the user's location (as indicated by their mobile phone).

In an exemplary arrangement, the central scheduling system 310 can be a server or group of servers configured to receive scheduling message requests and/or scheduling instructions from the access system 302. Such a dispatch message may request or instruct the central dispatch system 310 to coordinate the deployment of the UAV to various target locations. The central scheduling system 310 may be further configured to route such requests or instructions to one or more local scheduling systems 312. To provide such functionality, the central scheduling system 310 may communicate with the access system 302 via a data network, such as the internet, or a private network established for communication between the access system and the automated scheduling system.

In the illustrated configuration, the central dispatch system 310 may be configured to coordinate the dispatch of UAVs 304 from many different local dispatch systems 312. As such, the central dispatch system 310 may track which UAVs 304 are located in which local dispatch systems 312, which UAVs 304 are currently available for deployment, and/or for which services or operations each UAV304 is configured for (in the case where the UAV fleet includes multiple types of UAVs configured for different services and/or operations). Additionally or alternatively, each local dispatch system 312 may be configured to track which of its associated UAVs 304 are currently available for deployment and/or are currently in item transit.

In some cases, when the central dispatch system 310 receives a request from the access system 302 for a service related to a UAV (e.g., transportation of an item), the central dispatch system 310 may select a particular UAV304 to dispatch. The central dispatch system 310 may accordingly instruct the local dispatch system 312 associated with the selected UAV to dispatch the selected UAV. The local dispatch system 312 can then operate its associated deployment system 314 to launch the selected UAV. In other cases, the central dispatch system 310 may forward the request for services related to the UAV to a local dispatch system 312 near the location of the request support and leave the selection of the particular UAV304 to the local dispatch system 312.

In an example configuration, the local scheduling system 312 may be implemented as a computing system at the same location as the deployment system(s) 314 it controls. For example, the local dispatch system 312 can be implemented by a computing system installed at a building, such as a warehouse, where the deployment system(s) 314 and UAV(s) 304 associated with a particular local dispatch system 312 are also located. In other implementations, the local dispatch system 312 can be implemented at a location remote from its associated deployment system(s) 314 and UAV(s) 304.

Many variations and alternatives of the illustrated configuration of the UAV system 300 are possible. For example, in some implementations, a user of the remote device 306 may request delivery of a package directly from the central scheduling system 310. To this end, an application may be implemented on the remote device 306 that allows the user to provide information about the requested delivery and generate and send a data message to request the UAV system 300 to provide the delivery. In such embodiments, the central dispatch system 310 may include automated functionality to process requests generated by such applications, evaluate such requests, and coordinate with an appropriate local dispatch system 312 to deploy the UAV, if appropriate.

Moreover, some or all of the functionality attributed herein to central scheduling system 310, local scheduling system(s) 312, access system 302, and/or deployment system(s) 314 may be combined in a single system implemented as a more complex system and/or redistributed among central scheduling system 310, local scheduling system(s) 312, access system 302, and/or deployment system(s) 314 in various ways.

Further, although each local scheduling system 312 is shown with two associated deployment systems 314, a given local scheduling system 312 may alternatively have more or fewer associated deployment systems 314. Similarly, although the central scheduling system 310 is shown as communicating with two local scheduling systems 312, the central scheduling system 310 may alternatively communicate with more or fewer local scheduling systems 312.

In another aspect, the deployment system 314 may take various forms. In general, the deployment system 314 may take the form of or include a system for physically launching one or more UAVs 304. Such launch systems may include features that provide automatic UAV launch and/or features that allow for human-assisted UAV launch. Further, the deployment systems 314 may each be configured to launch one particular UAV304, or to launch multiple UAVs 304.

The deployment system 314 may also be configured to provide additional functionality, including, for example, functionality related to diagnostics, such as verifying system functionality of the UAV, verifying functionality of a device housed within the UAV (e.g., a payload delivery apparatus), and/or maintaining functionality of a device or other item housed in the UAV (e.g., by monitoring a state of a payload, such as its temperature, weight, etc.).

In some implementations, the deployment system 314 and its corresponding UAV304 (and possibly the associated local dispatch system 312) can be strategically distributed throughout an area such as a city. For example, the deployment systems 314 may be strategically distributed such that each deployment system 314 is proximate to one or more payload pick-up locations (e.g., near a restaurant, store, or warehouse). However, depending on the particular embodiment, deployment system 314 (and possibly local scheduling system 312) may be distributed in other ways. As a further example, kiosks may be installed at various locations that allow users to transport packages via UAVs. Such kiosks may include a UAV launch system, and may allow users to provide their packages to load onto the UAV and pay for UAV delivery services, and the like. Other examples are also possible.

In another aspect, the UAV system 300 may include or have access to a user account database 316. The user account database 316 may include data for a number of user accounts, and each user account is associated with one or more persons. For a given user account, the user account database 316 may include data related to or useful in providing services related to the UAV. Typically, user data relating to each user account is optionally provided by and/or collected under the permission of the associated user.

Further, in some embodiments, if a person wishes to be provided UAV related services by UAV304 from UAV system 300, they may be required to register a user account with UAV system 300. As such, the user account database 316 may include authorization information (e.g., username and password) for a given user account and/or other information that may be used to authorize access to the user account.

In some implementations, people can associate their one or more devices with their user accounts so that they can access the services of the UAV system 300. For example, when a person uses an associated mobile phone, e.g., calls the operator of the access system 302 or sends a message to the dispatch system requesting a service related to the UAV, the phone may be identified via the unique device identification number and the call or message may then be attributed to the associated user account. Other examples are also possible.

Exemplary rotor unit

Figure 4 depicts a cross-section of a stacked rotor blade 400 according to an example embodiment. Stacked rotor blade 400 is shaped like an airfoil such that when stacked rotor blade 400 moves in air (or other medium in other examples), the differences in pressure and relative velocity caused in part by cross-sectional profile 402 of stacked rotor blade 400 generate aerodynamic forces, including lift, on stacked rotor blade 400. Stated differently, as air flows through stacked rotor blade 400, the flow may generally follow a contour 402 of stacked rotor blade 400.

Stacked rotor blade 400 includes a plurality of blade elements 402A-402F (i.e., a first blade element 402A, a second blade element 402B, a third blade element 402C, a fourth blade element 402D, a fifth blade element 402E, and a sixth blade element 402F). Although six blade elements are shown in fig. 4, in various embodiments, stacked rotor blade 400 may include more or less than six blade elements.

While most airfoil designs avoid stepped or abruptly changing edges, the low reynolds number hydrodynamic conditions for the bladeletts, such as used in the UAV described herein, are not detrimental to the bladeletts which are stair-stepped or non-smooth. In this manner, stacking individual blades, such as blade elements 402A-402F, allows for relatively low cost and efficient production of rotor blades without requiring advanced machining, shaping, and bending of the rotor blades. Instead, as shown in FIG. 4, a plurality of planar blade elements (e.g., blade elements 402A-402F) may be stacked one on top of the other to create an airfoil profile, such as profile 402.

In some aspects, the characteristics of each blade element (e.g., leading edge, trailing edge, chord, span length, camber, angle of attack, pitch, etc.) may form a portion of the associated characteristics of stacked rotor blade 400 or of stacked rotor blade 400. For example, each of the blade elements 402A-402F may include a leading edge. In one example, the leading edge of stacked rotor blade 400 may include at least a portion of a first leading edge of first blade element 402A and at least a portion of a second leading edge of second blade element 402B. Similarly, in an example, at a first radial distance from the axis of rotation, a chord of stacked rotor blade 400 may be greater than a chord of each of the individual blade elements 402A-402F. In other examples, the span of stacked rotor blade 400 may be greater than the span of each of the individual blade elements 402A-402F.

Moreover, in other aspects, the material properties of each blade element may generally contribute to the design and function of stacked rotor blade 400. For example, blade elements 402A-402B and blade elements 402E-402F may be constructed of a very light material to keep the mass and/or weight of stacked rotor blade 400 low. However, blade elements 402C-402D may be constructed of a denser or heavier material that provides additional rigidity and robustness to stacked rotor blade 400. In other examples, the materials of the various blade elements 402A-402F may vary in elasticity, yield strength, ductility, toughness, and the like, individually or in combination. In some examples, the plurality of blade elements 402A-402F may be constructed from fiber sheets, plastics, composites, metals, wood, and other materials. In some examples, blade elements 402A-402F may include or be at least partially constructed from piezoelectric patches that may allow further acoustic control by providing feedback from stacked rotor blades 400 to a control system.

In some embodiments, there may be gaps between the vane elements 402A-402F in the axial direction. The axial direction is a direction parallel to the axis of rotation of stacked rotor blade 400. However, in other embodiments, the blade elements 402A-402F may be secured together via alignment features or a bonding material such as glue or another adhesive.

In an example, first blade element 402A, second blade element 402B, third blade element 402C, fourth blade element 402D, fifth blade element 402E, and sixth blade element 402F are arranged in a stacked configuration. As shown in fig. 4, the stacked configuration of stacked rotor blades 400 defines a profile 402 of stacked rotor blades 400. The stacked configuration of the blade elements 402A-402F or the alignment of the blade elements 402A-402F relative to one another may be based on desired flight characteristics or a preferred airfoil profile, such as profile 402. For example, profile 402 may be described as a low camber, thick wing design. In such an example, each of the blade elements 402A-402F may be planar or relatively flat. As such, each of the blade elements 402A-402F may include a top planar surface and a bottom planar surface. In an example, at least a portion of the bottom planar surface of the second blade element 402B may be secured to at least a portion of the top planar surface of the first blade element 402A. Further, each of the blade elements 402A-402F may be arranged in a stacked configuration such that the blade elements 402A-402F are directly on top of one another. In other examples, the low camber, thick wing design of FIG. 4 may result in the profile 402 having a substantially flat bottom with low camber.

In other arrangements, the blade elements 402A-402F may be stacked such that at least a portion of at least one of a top surface or a bottom surface of each of the blade elements 402A-402F is secured to at least a portion of a corresponding top surface or bottom surface of an adjacent blade element. For example, as depicted in FIG. 4, a portion of a first blade element 402A is secured to a portion of an adjacent second blade element 402B. In other aspects, the blade elements 402A-402F may be stacked such that at least a portion of each of the blade elements 402A-402F overlaps at least a portion of an adjacent blade element. For example, a portion of the third blade element 402C may overlap a portion of the second blade element 402B.

Figure 5 depicts a cross-section of a stacked rotor blade 500 according to an example embodiment. Stacked rotor blade 500 may be similar to stacked rotor blade 400 of fig. 4, but profile 502 of stacked rotor blade 500 may be different than profile 402 of stacked rotor blade 400. In an example, the stacked rotor blade 500 may include a plurality of blade elements 502A-502E. Unlike fig. 4, in other examples, each of the vane elements 502A-502E may be non-planar, and each vane element may have a curved shape. In some embodiments, blade elements 502A-502E may be cambered elements, each having a camber that may form the camber of stacked rotor blade 500. As such, the profile 502 may be based on an arrangement of stacked configurations of the blade elements 502A-502E. Further, the profile 502 may be based on aspects of the blade elements 502A-502E that may form or make up a portion of relevant aspects of the stacked rotor blade 500.

Fig. 6A and 6B depict stacked blade rotor units 600 according to an example embodiment. Rotor unit 600 may take the form of or be similar in form to the rotors described above in fig. 1A-1E. Furthermore, the components and aspects of rotor unit 600 may take a form and function similar to the components and aspects of the rotor described in fig. 1A-1E.

As shown in fig. 6A and 6B, rotor unit 600 includes two stacked rotor blades 602. Stacked rotor blade 602 may have similar aspects as stacked rotor blade 400 of fig. 4 and/or stacked rotor blade 500 of fig. 5. Although two stacked rotor blades 602 are depicted, other embodiments contemplated herein may include more than two stacked rotor blades. Rotor unit 600 also includes a hub 630 coupled to stacked rotor blades 602. In an example, hub 630 may be coupled to the root of stacked rotor blades 602. Hub 630 may include or be coupled to an electric motor that drives rotation of hub 630 and stacked rotor blades 602 about axis 640 in a first rotational direction 642. Each stacked rotor blade 602 includes a plurality of blade elements, which as shown in fig. 6A and 6B include a first blade element 606, a second blade element 610, a third blade element 614, and a fourth blade element 618. Although the plurality of blade elements depicted in fig. 6A and 6B are depicted as having four blades (i.e., 606, 610, 614, and 618), more or fewer blades are also contemplated herein.

Each stacked rotor blade 602 includes a leading edge 602A and a trailing edge 602B. Further, each of the plurality of vane elements also includes a leading edge and a trailing edge. For example, as depicted in fig. 6A and 6B, the first blade element 606 includes a leading edge 606A and a trailing edge 606B, the second blade element 610 includes a leading edge 610A and a trailing edge 610B, the third blade element 614 includes a leading edge 614A and a trailing edge 614B, and the fourth blade element 618 includes a leading edge 618A and a trailing edge 618B. In an example, the leading edge 602A of the stacked rotor blade 602 may be formed by the leading edges of the plurality of blade elements. For example, at least a portion of leading edge 606A, leading edge 610A, and leading edge 614A may combine to form leading edge 602A. In some examples, when the stacked rotor blade 602 rotates in the first rotational direction 642, at least a portion of the first leading edge 606A leads the second leading edge 610A or the second leading edge 610A in the first rotational direction 642.

Additionally, stacked rotor blade 602 may have a chord dimension 602C ("chord 602C") and a span dimension ("span 602D"). The chord dimension includes the length of the chord line, which is the line joining the ends of the midline of the rotor blade at a radial distance outward from the axis 640. In other words, a chord is the length from the leading edge of a rotor blade (or blade element) to the trailing edge of the rotor blade (or blade element). In some examples, the chord may vary with radial distance, while in other examples, the chord may be the same or nearly the same over the entire or nearly the entire span of the rotor blade. Similarly, the span dimension of a rotor blade is the linear length from the tip of the rotor blade (or the furthest point of the rotor blade radially outward from the axis of rotation) to the root of the rotor blade (or the closest point of the rotor blade radially to the axis of rotation).

Each blade element of the plurality of blade elements also includes a chord dimension and a span dimension. For example, first blade element 606 includes chord 606C and span 606D. Although each dimension is not shown, it should be understood that each of the other blade elements have similar dimensional aspects. For example, second blade element 610 includes chord 610C (not depicted) and span 610D (not depicted), third blade element 614 includes chord 614C (not depicted) and span 614D, and fourth blade element 618 includes chord 618C and span 618D (not depicted).

In an example, the plurality of blade elements may form a stacked rotor blade 602, such that dimensional aspects of stacked rotor blade 602 may be based on similar aspects of the plurality of blade elements. For example, as shown in fig. 6A and 6B, third blade element 614 may have a span 614D that is the same as span 602D of stacked rotor blade 602. In such examples, the third blade element 614 may also have a maximum span (i.e., a length from the root to the tip) of each of the plurality of blade elements. Continuing with this example, as shown in fig. 6A and 6B, span 602D of stacked rotor blade 602 is greater than span 606D of first blade element 606, span 610D of second blade element 610, and span 618D of fourth blade element 618. Further, different blade elements may have different spans than other blade elements. For example, in other examples, stride 610D may be greater than stride 606D.

In some aspects, chord 602C of stacked rotor blade 602 may include at least a portion of chord 606C of first blade element 606, chord 610C of second blade element 610, chord 614C of third blade element 614, and chord 618C of fourth blade element 618. Similarly, chord 602C of stacked rotor blade 602 may be greater than any of the individual chords (e.g., 606C, 610C, 614C, and 618C) of the plurality of blade elements.

In an example, the plurality of vane elements may have additional relational features. For example, as shown in the top view of fig. 6A, the tip of first blade element 606 may be radially aligned with leading edge 610A of second blade element 610 (i.e., aligned along an axis parallel to axis 640). Similarly, the tip of the second blade element 610 may be aligned with the leading edge 614A of the third blade element 614. In such examples, each of the plurality of blade elements may be radially offset from each other relative to axis 640. More specifically, for example, first blade element 606 may be radially offset from second blade element 610. The radial alignment of each of the plurality of blade elements may be at least a feature of the stacked configuration of the blade elements, among other possible features.

The stacked configuration of stacked rotor blades 602 may be based on the relative size and alignment/arrangement of the blade elements with respect to each other. The described stacked alignment and orientation may allow the stacked rotor blades 602 to provide the necessary thrust and lift as part of the UAV, while also reducing noise and allowing quiet flight of the UAV. Moreover, designers and operators may have additional control over flight and noise as compared to another UAV, because with stacked rotor blades 602, designers and operators may have more customizable options in designing and selecting combinations and orientations of blade elements for a UAV that may function more efficiently or more effectively for the intended purpose. For example, various orientations and alignments may allow for easily customizable pitch, camber, angle of attack, control of rotor surface area, and the like, as compared to a single-piece rotor.

For example, an operator may determine specific flight characteristics necessary for certain flight missions and be able to create or select customized rotors specific to those flight missions. In one example, a flight mission may include carrying heavy payload, and thus, rotors with high angles of attack that generate a greater amount of lift may be more desirable. With stacked rotor blades 602, an operator may align multiple blade elements with larger surface areas and higher angles of attack in order to provide more lift than a standard UAV rotor. As such, in an example, the angle of attack of stacked rotor blade 602 may be based on a first angle of attack of first blade element 606 and a second angle of attack of second blade element 610. The angle of attack of stacked rotor blade 602 may be further based on the third angle of attack of third blade element 614 and the fourth angle of attack of fourth blade element 618.

In another example, the operator may determine that a more resilient rotor would be preferable. In this way, an operator may select a stacked rotor blade, such as one of stacked rotor blades 602, wherein, for example, first blade element 606, second blade element 610, and fourth blade element 618 may be comprised of a more resilient material than third blade element 614. Third blade element 614 may be constructed of a more rigid material to provide support to stacked rotor blade 602. In short, stacked rotor blades 602 allow for easy construction of various rotor sizes, orientations, material properties, and the like.

Continuing with the figures, fig. 7 depicts a stacked-blade rotor unit 700 according to an example embodiment. Rotor unit 700 may take the form of rotor unit 600 of fig. 6A and 6B and/or the rotors described above in fig. 1A-1E or be similar in form. Furthermore, components and aspects of rotor unit 700 may take a form and function similar to components and aspects of rotor unit 600 of fig. 6A and 6B and/or rotors described in fig. 1A-1E.

As shown in fig. 7, the rotor unit 700 includes two stacked rotor blades 702. Stacked rotor blade 702 may have similar aspects as stacked rotor blade 400 of fig. 4 and/or stacked rotor blade 500 of fig. 5. Rotor unit 700 also includes a hub 730 coupled to stacked rotor blades 702. Hub 730 may include or be coupled to an electric motor that drives rotation of hub 730 and stacked rotor blades 702 about axis 740. Each stacked rotor blade 702 includes a plurality of blade elements including a first blade element 706, a second blade element 710, a third blade element 714, and a fourth blade element 718 as depicted in fig. 7. Similar to fig. 4A and 4B, each of the plurality of blade elements may have a leading edge (e.g., 706A, 710A, 714A, and 718A) and a trailing edge (e.g., 706B, 710B, 714B, and 718B). These leading and trailing edges may be aligned and/or combined to form the leading edge 702A and the trailing edge 702B of the stacked rotor blade 702.

FIG. 7 illustrates a blade element design that may be simpler and/or more cost effective to implement in certain scenarios. Each of the plurality of blade elements (706, 710, 714, and 718) may have the same or similar shape, but have different lengths. Furthermore, each of the plurality of blade elements may be planar in some embodiments, or may have a very small pitch in other embodiments. The plurality of blade elements may be coupled to hub 730 at various locations to create desired rotor characteristics for stacked rotor blades 702. In an example, a straight-edge design of the plurality of blade elements (706, 710, 714, and 718) similar to that shown in fig. 7 may be relatively simpler and less expensive to produce than other rotor blades, while still maintaining the ability to design and meet the flight characteristics required for stacked rotor blade 702.

Fig. 8 depicts a cross-section of a stacked-blade rotor unit 800 according to an example embodiment. Rotor unit 800 may take the form of rotor unit 700 of fig. 7, rotor unit 600 of fig. 6A and 6B, and/or the rotors described above in fig. 1A-1E, or be similar in form. Furthermore, components and aspects of rotor unit 800 may take a form and have similar functionality to components and aspects of rotor unit 700 of fig. 7, rotor unit 600 of fig. 6A and 6B, and/or the rotors described in fig. 1A-1E.

As shown in fig. 8, rotor unit 800 includes stacked rotor blades 802. Stacked rotor blade 802 may have similar aspects as stacked rotor blade 400 of fig. 4 and/or stacked rotor blade 500 of fig. 5. Rotor unit 800 also includes a hub 830 coupled to stacked rotor blades 802. Hub 830 may include or be coupled to a motor that drives the rotation of hub 830 and stacked rotor blades 802. Stacked rotor blade 802 includes a plurality of blade elements including first blade element 806, second blade element 810, third blade element 814, and fourth blade element 818 as depicted in fig. 8.

As depicted in fig. 8, each of the plurality of blade elements (i.e., 806, 810, 814, and 818) may be individually coupled to hub 830. The hub 830 may include a slot or recessed point where such blade elements may be connected to the hub 830. In such examples, hub 830 may provide indexing (indexing) and orientation of the plurality of blade elements. As shown, there may be a first gap 860A between first blade element 806 and second blade element 810, a second gap 860B between second blade element 810 and third blade element 814, and a third gap 860C between third blade element 814 and fourth blade element 818. The size of gaps 860A-C may be based on the indexing and orientation of the plurality of vane elements.

Fig. 9 depicts a cross-section of a stacked-blade rotor unit 900 according to an example embodiment. Rotor unit 900 may take the form of rotor unit 800 of fig. 8, rotor unit 700 of fig. 7, rotor unit 600 of fig. 6A and 6B, and/or the rotors described above in fig. 1A-1E, or similar in form. Furthermore, components and aspects of rotor unit 900 may take a form and have similar functionality to components and aspects of rotor unit 800 of fig. 8, rotor unit 700 of fig. 7, rotor unit 600 of fig. 6A and 6B, and/or the rotors described in fig. 1A-1E.

As shown in fig. 9, rotor unit 900 includes stacked rotor blades 902. Stacked rotor blade 902 may have similar aspects as stacked rotor blade 400 of fig. 4 and/or stacked rotor blade 500 of fig. 5. Rotor unit 900 also includes a hub 930 coupled to stacked rotor blades 902. Hub 930 may include or be coupled to an electric motor that drives the rotation of hub 930 and stacked rotor blades 902. The stacked rotor blade 902 includes a plurality of blade elements, which as depicted in fig. 9, includes a first blade element 906, a second blade element 910, a third blade element 914, and a fourth blade element 918.

Fig. 9 illustrates a passive mechanical alignment feature that aligns, orients, and/or indexes the plurality of vane elements. In some examples, hub 930 may include an active indexing mechanism, such as a clamp nut, that urges and holds the plurality of blade elements together such that the alignment features of the plurality of blade elements are coupled together. The clamping nuts of the hub 930 may maintain the overall alignment of the plurality of blade elements. Other mechanical means of maintaining the vane elements in a particular position are contemplated herein. Even with the indexing means, there may still be a first gap 960A, a second gap 960B and a third gap 960C.

In an example, the first blade element 906 may include a first alignment feature, the second blade element 910 may include a second alignment feature coupled to the first alignment feature, the third blade element 914 may include a third alignment feature coupled to the second alignment feature, and the fourth blade element 918 may include a fourth alignment feature coupled to the third alignment feature.

As depicted in FIG. 9, the second blade element 910 may include a first protrusion 950A, the third blade element 914 may include a second protrusion 950B, and the fourth blade element 918 may include a third protrusion 950C. Each of the raised features 950A-C may be positioned on a top surface of a respective blade element. In some examples, the protrusions 950A-C may be dome-shaped. The first blade element 906 may have a first recessed alignment feature (e.g., a recessed dome shape) shaped similar to the first protrusion 950A, such that the protrusion 950A fits at least partially within the recessed feature. In some examples, the protrusion 950A is configured to mate with a recess or recessed feature of the first blade element 906. As such, first protrusion 950A may correspond to a recessed alignment feature and may maintain the relative positioning or alignment of first blade element 906 with respect to second blade element 910. In some aspects, first protrusion 950A of second blade element 910 may be coupled to a recessed alignment feature of first blade element 906.

Similarly, second blade element 910 may have a second recessed alignment feature shaped similarly to second raised feature 950B such that the alignment features correspond to each other, and the relative positioning of second blade element 910 with respect to third blade element 914 may be maintained (or the amount of movement between second blade element 910 and third blade element 914 limited). In some aspects, second protrusion 950B of third blade element 914 may be coupled to a recessed alignment feature of second blade element 910. Additionally, in some examples, the third blade element 914 may have third recessed alignment features shaped similar to the third protrusion 950C such that the alignment features correspond to one another and may maintain the relative positioning of the third blade element 914 with respect to the fourth blade element 918. In some aspects, the third protrusion 950C of the fourth blade element 918 may be coupled to a recessed alignment feature of the third blade element 914.

Fig. 10 depicts a cross-section of a stacked-blade rotor unit 1000 according to an example embodiment. Rotor unit 1000 may take the form of rotor unit 900 of fig. 9, rotor unit 800 of fig. 8, rotor unit 700 of fig. 7, rotor unit 600 of fig. 6A and 6B, and/or the rotors described above in fig. 1A-1E, or be similar in form. Furthermore, components and aspects of rotor unit 1000 may take a form similar to, and function similarly to, components and aspects of rotor unit 900 of fig. 9, rotor unit 800 of fig. 8, rotor unit 700 of fig. 7, rotor unit 600 of fig. 6A and 6B, and/or the rotors described in fig. 1A-1E.

As shown in fig. 10, rotor unit 1000 includes stacked rotor blades 1002. Stacked rotor blade 1002 may have aspects similar to stacked rotor blade 400 of fig. 4 and/or stacked rotor blade 500 of fig. 5. Rotor unit 1000 also includes a hub 1030 that is coupled to stacked rotor blades 1002. Hub 1030 may include or be coupled to an electric motor that drives the rotation of hub 1030 and stacked rotor blades 1002. Stacked rotor blade 1002 comprises a plurality of blade elements, as depicted in fig. 10, including a first blade element 1006, a second blade element 1010, a third blade element 1014, and a fourth blade element 1018.

Unlike

rotor units

800 and 900 of fig. 8 and 9, respectively, there are no gaps between the plurality of blade elements of fig. 10. In an example, the plurality of vane elements may be joined and/or coupled together using an adhesive layer between the vane elements or an adhesive such as glue. For example, first blade element 1006 may be coupled to second blade element 1010 in a stacked configuration or in a particular alignment with each other by adhesive 1070A. Similarly, second blade element 1010 may be coupled to third blade element 1014 by adhesive 1070B, and third blade element 1014 may be coupled to fourth blade element 1018 by adhesive 1070C. In some examples, adhesives 1070A-1070C may be interface sheets constructed from piezoelectric sheets that may be coupled between surfaces of blade elements. In some embodiments, the plurality of blade elements may be aligned and joined together prior to coupling to hub 1030.

Fig. 11 depicts yet another stacked-blade rotor unit 1100 according to an example embodiment. Rotor unit 1100 may take the form of, or be similar in form to, rotor unit 1000 of fig. 10, rotor unit 900 of fig. 9, rotor unit 800 of fig. 8, rotor unit 700 of fig. 7, rotor unit 600 of fig. 6A and 6B, and/or the rotors described above in fig. 1A-1E. Furthermore, components and aspects of rotor unit 1100 may take a form and have similar functionality to components and aspects of rotor unit 1000 of fig. 10, rotor unit 900 of fig. 9, rotor unit 800 of fig. 8, rotor unit 700 of fig. 7, rotor unit 600 of fig. 6A and 6B, and/or the rotors described in fig. 1A-1E.

As shown in fig. 11, rotor unit 1100 includes three stacked rotor blades 1102. Stacked rotor blade 1102 may have similar aspects as stacked rotor blade 400 of fig. 4 and/or stacked rotor blade 500 of fig. 5. Although three stacked rotor blades 1102 are depicted, more than three stacked rotor blades are also contemplated herein. Rotor unit 1100 also includes a hub 1130 coupled to stacked rotor blades 1102. Hub 1130 may include or be coupled to an electric motor that drives rotation of hub 1130 and stacked rotor blades 1102 about an axis. Each stacked rotor blade 1102 includes a plurality of blade elements, which as depicted in fig. 11 include a first blade element 1106, a second blade element 1110, and a third blade element 1114. Although each stacked rotor blade 1102 is depicted as having the plurality of blade elements including three blades (i.e., 1106, 1110, and 1114), more and fewer blades are contemplated herein as part of each of the plurality of blade elements of stacked rotor blade 1102.

Each of the plurality of vane elements includes a leading edge (e.g., 1106A, 1110A, and 1114A) and a trailing edge (e.g., 1106B, 1110B, and 1114B). Further, leading

edges

1106A, 1110A, and 1114A form leading edge 1102A of stacked rotor blade 1102, and further, trailing

edges

1106B, 1110B, and 1114B form trailing edge 1102B of stacked rotor blade 1102. Although 1102A has identified the leading edge and 1102B has identified the trailing edge, in other examples, the trailing edge and the leading edge may be reversed. That is, the opposite orientation is also contemplated herein.

FIG. 11 also shows an example where the first blade element 1106 may be radially offset from the second blade element 1110 by an angle 1108. Similarly, the second blade element 1110 may be radially offset from the third blade element 1114 by an angle 1112. The amount of offset, i.e., the size of angle 1108 and angle 1112, may allow for control of the features of stacked rotor blade 1102, such as the angle of attack, camber, and surface area of stacked rotor blade 1102, etc. In some examples, angle 1108 may be equal to angle 1112, while in other examples, angle 1108 may be different from angle 1112.

Fig. 12 depicts a partial view of a rotor unit 1200 according to an example embodiment. Rotor unit 1200 may take the form of, or be similar in form to, rotor unit 1100 of fig. 11, rotor unit 1000 of fig. 10, rotor unit 900 of fig. 9, rotor unit 800 of fig. 8, rotor unit 700 of fig. 7, rotor unit 600 of fig. 6A and 6B, and/or the rotors described above in fig. 1A-1E. Furthermore, components and aspects of rotor unit 1200 may take a form and have similar functionality to components and aspects of rotor unit 1100 of fig. 11, rotor unit 1000 of fig. 10, rotor unit 900 of fig. 9, rotor unit 800 of fig. 8, rotor unit 700 of fig. 7, rotor unit 600 of fig. 6A and 6B, and/or the rotors described in fig. 1A-1E.

As shown in fig. 12, rotor unit 1200 includes stacked rotor blades 1202. Stacked rotor blade 1102 may have similar aspects as stacked rotor blade 400 of fig. 4 and/or stacked rotor blade 500 of fig. 5. Rotor unit 1200 also includes a hub 1230 that is coupled to stacked rotor blades 1202. Hub 1230 may include or be coupled to an electric motor that drives the rotation of hub 1230 and stacked rotor blades 1202. The stacked rotor blade 1202 includes a plurality of blade elements including a first blade element 1206, a second blade element 1210, and a third blade element 1214, as depicted in fig. 12.

As depicted in fig. 12, the plurality of blade elements may include other physical features to improve aerodynamic efficiency and control. For example, leading edge 1206A of first blade element 1206, leading edge 1210A of second blade element 1210, and leading edge 1214A of third blade element 1214 may be nodular. As such, the leading edge of stacked rotor blade 1202 may also be nodular. In other examples, the leading edge may be serrated, wavy, or various other shapes.

Further, FIG. 12 also provides another example alignment where the tip of first blade element 1206 overlaps the top surface of second blade element 1210. In an example, the leading edges of the plurality of blade elements (i.e., 1206A, 1210A, and 1214A) are radially aligned with one another. However, trailing edge 1206B of first blade element 1206, trailing edge 1210B of second blade element 1210, and trailing edge 1214B of third blade element 1214 may be offset from one another such that stacked rotor blade 1202 has a stepped downward orientation. In an example, as depicted in fig. 12, based on the alignment shown, the stacked rotor blades 1202 may have a small lower camber and a large upper camber. Other alignments and combinations of blade element orientations may produce other stacked rotor blade shapes.

Additionally, a method for manufacturing a stacked-blade rotor unit is disclosed. Figure 13 is a simplified block diagram illustrating a method 1300 for manufacturing stacked-blade rotor units, according to an example embodiment. It is to be appreciated that the example method, such as method 1300, may be implemented by an entity or combination of entities (i.e., by other computing devices and/or combinations thereof) without departing from the scope of the present invention.

For example, the functions of method 1300 may be performed entirely by a machine, a human operator, a computing device (or components of a computing device, such as one or more processors or controllers), or may be distributed across multiple components of a computing device, across multiple computing devices, and/or across servers. In some examples, the computing device may receive information from input commands initiated by an operator, sensors of the computing device, or may receive information from other computing devices that collect information.

As shown at block 1302, method 1300 includes cutting a plurality of blade elements. In an example, at least one dimension of each of the plurality of blade elements may be different from a corresponding dimension of each other of the plurality of blade elements. For example, the span of a first blade element may be different than the span of a second blade element, and so on. The blade elements may be laser cut or otherwise mechanically cut from sheet fiber, metal, plastic, and various other materials. In some examples, the blade elements or interface elements may be constructed of piezoelectric patches to provide more acoustic control of the stacked rotor blades.

As shown at 1304, method 1300 includes aligning the cut blade elements to form a stacked rotor blade. Design features of the stacked rotor blades (such as the leading edges of the stacked rotor blades, the profiles of the stacked rotor blades, chords of the stacked rotor blades, and the spans of the stacked rotor blades, among other features) may be based on corresponding features of the individual blade elements as well as the alignment and orientation of the blade elements relative to each other.

As shown at block 1306, method 1300 further includes coupling the plurality of blade elements to a hub. In some examples, the blade elements may be fixed to each other prior to coupling to the hub. In other examples, each blade element may be coupled to the hub at one time. In an example, the plurality of blade elements may be coupled to the hub such that the blade elements are radially offset from one another so as to produce a preferred or desired shape of the stacked rotor blade.

Conclusion IV

It should be understood that the arrangements described herein are for example purposes only. As such, those skilled in the art will appreciate that other arrangements and other elements (e.g., machines, interfaces, operations, orders, and groupings of operations, etc.) can be used instead, and some elements can be omitted altogether depending upon the desired results. Further, many of the elements described are functional entities that may be implemented as discrete or distributed components or in conjunction with other components, in any suitable combination and location, or may be combined with other structural elements described as a stand-alone structure.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope being indicated by the following claims, along with the full scope of equivalents to which such claims are entitled. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

Claims

1. A rotor unit comprising:

a hub configured to rotate in a first rotational direction about an axis; and

a stacked rotor blade secured to the hub such that the stacked rotor blade is rotatable about the axis, the stacked rotor blade comprising:

a first vane element including a first leading edge, and

a second blade element comprising a second leading edge,

wherein the first and second blade elements are arranged in a stacked configuration, an

Wherein at least a portion of the first leading edge and at least a portion of the second leading edge form a leading edge of the stacked rotor blade.

2. The rotor unit according to claim 1, wherein at a first radial distance from the axis, a chord of the stacked rotor blades is greater than each of a chord of the first blade element and a chord of the second blade element.

3. The rotor unit according to claim 1, wherein a span of the stacked rotor blades is greater than a span of the first blade element, and further wherein the span of the stacked rotor blades is greater than a span of the second blade element.

4. The rotor unit according to claim 1, wherein the first blade element is radially offset from the second blade element relative to the axis.

5. The rotor unit according to claim 1, wherein a tip of the first blade element is radially aligned with the leading edge of the second blade element.

6. The rotor unit according to claim 1, wherein the stacked rotor blade further comprises a third blade element having a span that is greater than a span of the second blade element, the length of the second blade element being greater than a span of the first blade element.

7. The rotor unit according to claim 1, wherein the first blade element further includes a first alignment feature, and further wherein the second blade element further includes a second alignment feature coupled to the first alignment feature.

8. The rotor unit according to claim 1, wherein the first alignment feature comprises a recess, and wherein the second alignment feature comprises a protrusion configured to mate with the recess.

9. The rotor unit according to claim 1, wherein the hub includes a clamp nut that maintains alignment between the first and second blade elements.

10. The rotor unit according to claim 1, wherein the first blade element is composed of a first material, wherein the second blade element is composed of a second material, and wherein the first material has a different elasticity than the second material.

11. The rotor unit according to claim 1, wherein at least a portion of the leading edge of the first blade element comprises a nodule.

12. The rotor unit according to claim 1, wherein an angle of attack of the stacked rotor blades is based on a combination of a first angle of attack of the first blade element and a second angle of attack of the second blade element.

13. The rotor unit according to claim 1, wherein the first blade element is planar.

14. The rotor unit according to claim 1, wherein the first blade element is non-planar.

15. The rotor unit according to claim 1, wherein the stacked configuration is arranged such that the first blade element is stacked directly on the second blade element.

16. The rotor unit according to claim 1, wherein the stacked configuration is arranged such that there is a gap in the axial direction between the first and second blade elements.

17. A stacked rotor blade, comprising:

a first planar blade element comprising a first leading edge and a bottom planar surface, an

A second planar blade element comprising a second leading edge and a top planar surface;

wherein the bottom planar surface is secured to the top planar surface in a stacked configuration,

wherein the stacked rotor blades are configured to rotate in a first rotational direction,

wherein at least a portion of the first leading edge leads the second leading edge in the first rotational direction, an

18. A method, comprising:

cutting a plurality of blade elements, wherein at least one dimension of each of the plurality of blade elements is different from a corresponding dimension of each other blade element of the plurality of blade elements;

aligning each of the plurality of cut blade elements to form a stacked blade, wherein the alignment of the plurality of cut blade elements also defines a contour of the stacked blade, and wherein a leading edge of the stacked blade comprises at least a portion of a leading edge from each of the plurality of cut blade elements; and

coupling the plurality of blade elements to a hub.

19. The method of claim 18, wherein aligning each of the plurality of cut leaves comprises:

coupling each of the plurality of cut blade elements to another of the plurality of cut blade elements such that each of the plurality of cut blade elements is radially offset from another of the plurality of cut blade elements relative to an axis of rotation, wherein the axis of rotation extends perpendicularly through a center of the hub.

20. The method of claim 18, wherein the plurality of blade elements are each cut from a fibrous sheet.